Neutral/Grounded wire

[aknoles]

Hello and thanks to all for your comments. My question is: does a Neutral/Grounded wire need to travel with the current carrying conductors (Hots) the entire way? Here is the scenario: A new generator is being added to an existing system. For each sub panel down line, two hots, neutral and ground are running continuous from the Main panel to the sub panel. At the main, the two hots for each panel are disconnected from the original breaker, and spliced from wire coming from an additional sub panel that has the two House sub panel and a shop sub panel disconnect. The complete system is Transfer switch to Sub panel with 3 sub panel disconnects (two for the house and one for the shop), and back thru/spliced at main panel. The question again is does the neutral wire for the two subs for the house and the sub for the shop need to travel through the transfer switch and to the sub panel with the three disconnects? Or is it okay for the 2 house and shop sub panels neutrals to come directly from the main panel and bypass the transfer switch and sub panel where the disconnects are landed.
Another way to ask this question is can the neutrals for any loads transfer to the new sub panel be left connected at the main panel or do they need to go along with the hots to the new sub panel?
Thank you!

 

[mopowr steve]

Good question,
I’ve thought of this briefly once when doing a ATS with loadcenter. Some would say it’s probably not compliant but sure seems like a waste of time and wire.

 

[roger]

It's a switch, think about any switch, run the ungrounded conductor(s) and switch leg(s)

Roger

 

[jaggedben]

I'm not sure your description is precisely enough to speak to completely. But there is only one situation in which a circuit's neutral doesn't have to be run with the hots. And that is where all hots run forward and back in the same conduit or cable to a device such as a switch or meter.

Also, wherever a circuit originates, the neutral must originate in the same location. So if the subpanel feeders are being rewired to a new sub, the neutrals need to move there.

 

[jaggedben]

is it okay for the 2 house and shop sub panels neutrals to come directly from the main panel and bypass the transfer switch and sub panel where the disconnects are landed.

No, because of the red part. It would be okay to bypass the transfer switch, assuming it does not switch the neutral and that the wiring methods are done properly.

 

[aknoles]

I'm not sure your description is precisely enough to speak to completely. But there is only one situation in which a circuit's neutral doesn't have to be run with the hots. And that is where all hots run forward and back in the same conduit or cable to a device such as a switch or meter.

Also, wherever a circuit originates, the neutral must originate in the same location. So if the subpanel feeders are being rewired to a new sub, the neutrals need to move there.

Thank you for your response, do you have a code section you are referring to when you say "wherever a circuit originates, the neutral must originate in the same location?"

 

[ActionDave]

300.3(B)

 

[kwired]

300.3(B)

I don't believe that section is necessarily saying that the neutral must be run in manner in discussion here.

I believe the main intent of 300.3(B) is to reduce magnetic effects on ferrous enclosures, raceways, etc. containing the conductors.

If you have a multiwire circuit (2 hots and neutral) in a junction box, make a drop in a ferrous raceway to a two pole switch with both "hots" then return conductors back to the junction box within same ferrous raceway, there is no need to also bring the neutral to switch box if it serves no load in that box, and not bringing it there does not present any magnetic effects on the raceway either.

We do this same thing quite frequently with just two conductors (a supply and a return in same raceway/cable) to a single pole switch as well.

I see nothing that changes this for say a panelboard like OP has, from 300.3(B) perspective anyway. could be something in some other part of code that might apply to the panelboard situation though.

 

[LarryFine]

I waited to respond until a few questions were asked and answered, to make sure I got the picture.

As KW said, as long as the conductors leaving any given enclosure are in the same raceway as those returning, there won't be any electromagnetic issues. A neutral would need to accompany them for a feeder leaving an enclosure.

As with any panel, a neutral only needs to sub-panels that have line-to-neutral loads.